ANKARA, Turkey -- Turkey is preparing to challenge Israel's blockade on Gaza at the International Court of Justice, the foreign minister said Saturday, ratcheting up tensions between the once close allies.

Ahmet Davutoglu's comments came a day after Turkey expelled Israel's ambassador and severed military ties with the country, angered over its refusal to apologize for last year's deadly raid on a Gaza-bound aid flotilla that killed nine pro-Palestinian activists.

In an interview with Turkey's state-run TRT television, Davutoglu dismissed a U.N. report into the raid that said Israel's naval blockade of Gaza was a legal security measure.

Davutoglu said the report prepared by former New Zealand Prime Minister Geoffrey Palmer and former Colombian President Alvaro Uribe, and presented to U.N. Secretary-General Ban Ki-moon <0x2014> was not endorsed by the United Nations and was therefore not binding.

"What is binding is the International Court of Justice," Davutoglu said. "This is what we are saying: let the International Court of Justice decide."